Escherichia coli F4ac fimbrial adhesin (F4ac) (F4ac)

The Escherichia coli F4ac fimbrial adhesin (F4ac), historically known as the K88ac antigen, is a critical virulence factor found on the surface of enterotoxigenic Escherichia coli (ETEC) strains that infect swine (PMID: 24501212). This proteinaceous appendage facilitates the attachment of the bacteria to specific carbohydrate receptors on the brush border of porcine intestinal epithelial cells, a prerequisite for colonization and subsequent toxin delivery (UniProt: P02971). The F4ac variant is one of the most prevalent serotypes associated with severe post-weaning diarrhea and neonatal colibacillosis in piglets globally (PMID: 15696021). Because adhesion is the first step in infection, this antigen is a primary target for veterinary vaccines, including both live attenuated oral formulations and inactivated parenteral products (MSD Animal Health). Therapeutic strategies also explore the use of anti-adhesive molecules, such as specific antibodies or carbohydrate mimetics, to block the interaction between the fimbriae and host receptors (PMID: 21851263). Understanding the structural variations of the major subunit, FaeG, is essential for developing broad-spectrum interventions against ETEC-related enteric diseases in the agricultural industry (PMID: 19146601).

Other names

K88ac antigenK88ac fimbriaeFaeG proteinF4ac fimbriaeK88ac adhesinF4ac adhesin

Induction of mucosal and systemic antibodies that bind to the F4ac fimbriae, thereby sterically hindering the attachment of enterotoxigenic Escherichia coli to host intestinal receptors (PMID: 24501212).